1. Field of the Invention
The present invention relates to power-on reset circuits generating a power-on reset pulse signal.
2. Description of Related Art
The mission function of an integrated circuit may be performed erratically without a reliable power-on reset circuit. Power-on reset circuits provide a delay in time from the initial voltage rise of the main voltage supply until the main voltage supply has risen sufficiently to predictably supply power to an integrated circuit or a portion of the integrated circuit. Commonly, the output of the power-on reset circuit is connected to an enable input of the circuitry performing the mission function of the circuit.
The power-on reset circuit of U.S. Pat. No. 5,936,444, relies on transistors having a zero threshold voltage. However, transistors having a zero threshold voltage add steps to the CMOS manufacturing process and thereby raise the cost substantially.
A need therefore exists for a power-on reset circuit which is not critically dependent on zero threshold voltage transistors to function.